private void FillIn(Expression xpath, XmlNode topContext)
{
//initialize the context node
XmlNode current = topContext;
//start looking down the document tree
for (int length = 1; length <= xpath.StepCount; ++length)
{
Expression sub = xpath.SubExpression(length);
//check to see if the node already exists...
XmlNodeList nodes = topContext.SelectNodes(sub.ToString(true), this._namespaces);
if (nodes.Count == 0)
{
//... and create it if it doesn't
LocationStep step = sub.LastStep;
if (step.IsAttribute)
{
XmlAttribute attribute = this._document.CreateAttribute(step.NodeTest.Test);
current.Attributes.Append(attribute);
current = attribute;
}
else
{
string namespaceUri = this._namespaces.LookupNamespace(step.NodeTest.Namespace);
XmlNode element = this._document.CreateElement(step.NodeTest.Namespace, step.NodeTest.Test, namespaceUri);
current.AppendChild(element);
current = element;
}
//if there were attribute filters applied to the xpath, then apply them here
if (step.Predicates.Count > 0)
{
foreach (Predicate predicate in step.Predicates)
{
if (predicate.IsAttributeFilter)
{
XmlAttribute attribute = this._document.CreateAttribute(predicate.FilterKey.Substring(1));
attribute.Value = predicate.FilterValue;
current.Attributes.Append(attribute);
}
}
}
}
else if (nodes.Count == 1) //...otherwise, advance the context
{
current = nodes[0];
}
else //in the case of multiples, do it to all of them
{
foreach (XmlNode child in nodes)
{
FillIn(xpath.SubExpression(length, xpath.StepCount - length), child);
}
}
}
}
/// <summary>
/// Adds a location step to the end of the xpath, if the current xpath does not reference an Attribute
/// </summary>
/// <param name="locationStep"></param>
public void AddStep(LocationStep locationStep)
{
if (!this.IsAttribute)
{
this._components.Add(locationStep);
}
if (this._standardPrefix != null)
{
locationStep.NodeTest.Namespace = this._standardPrefix;
}
}
/// <summary>
/// Compares two location steps for equality. They must represent the same Axis Specifier, same Node Test
/// and equivalent sets of Predicates.
/// </summary>
/// <param name="obj"></param>
/// <returns></returns>
public override bool Equals(object obj)
{
if (obj is LocationStep)
{
LocationStep step = (LocationStep)obj;
return(this.ToString(true).Equals(step.ToString(true)));
}
else
{
return(false);
}
}
public LocationStep GetLocationStepByNodeTest(string p)
{
LocationStep locationStep = null;
foreach (LocationStep step in this._components)
{
if (step.NodeTest.Test.Equals(p))
{
locationStep = step;
}
}
return(locationStep);
}
/// <summary>
/// Tokenizes a provided XPath expression
/// </summary>
/// <param name="exp"></param>
public Expression(string exp)
: this()
{
try
{
exp = exp.Replace("//", "/descendant::");
if (exp[0] == '/')
{
this._isFromRoot = true;
exp = exp.Substring(1);
}
else
{
this._isFromRoot = false;
}
string[] parts = exp.Split('/');
string namespacePrefix = null;
bool allHavePrefix = true;
foreach (string part in parts)
{
LocationStep step = new LocationStep(part);
this._components.Add(step);
if (step.NodeTest.Namespace == null || (namespacePrefix != null && !step.NodeTest.Namespace.Equals(namespacePrefix)))
{
allHavePrefix = false;
}
else
{
namespacePrefix = step.NodeTest.Namespace;
}
}
if (allHavePrefix)
{
this._standardPrefix = namespacePrefix;
}
}
catch (Exception exception)
{
throw new Exception(string.Format("Could not construct XPath expression from input string(\"{0}\")", exp), exception);
}
}
